hate to ask the obvious questions here, but what year car did the donor engine come out of? i guess start with the obvious and verify its getting fuel, and then spark.
There are 3 lines that run from the passenger side of the engine bay, over across the intake manifold... Make sure those 3 lines are hooked up correctly. Fuel, return, and coolant if I recall correctly.
How long does it sit there and crank for before it finally catches?